1. Field of the Invention
This invention relates to energy absorbing composites suitable to replace steel panels, for instance, in automobile construction and reinforcing members useful as a reinforcing core therein.
2. Description of the Prior Art
Lightening the weight of automotive vehicles is desirable from the standpoint of increasing the efficiency with a resulting savings of energy. Weight lightening can be accomplished by reducing the thickness of metallic vehicle outer panels or by decreasing the number and thickness of structural members. However, this unavoidably lowers the strength of various component parts and causes a reduction in rigidity of an outer body panel, particularly in the case of an automobile vehicle door. Improved automobile bodypanels which are composites of a metal panel and a laminated plastic sheet attached to the metal panel are disclosed in U.S. Pat. No. 4,830,908.
Energy absorbing structures suitable for use in a motor vehicle body panel are disclosed in U.S. Pat. No. 4,545,172. The panels have the ability to absorb impact loads in a longitudinal direction. They comprise a wall having a plurality of ridges extending in a longitudinal direction corresponding to the expected direction of an applied load. Such structures undergo progressive collapse under impact in the longitudinal direction. The assemblies are made of a metal such as aluminum.
In U.S. Pat. No. 4,034,137, there is disclosed composite resin sheet structures to provide light weight, high strength panels which can be of flat or curved construction for use in place of sheet steel for automotive vehicle bodies and body parts. These are improved laminated sheet structures comprising resilient open-celled resin foam impregnated with a thermosetting resin and compressed and bonded to surface layers of thermosetting resin-impregnated fibrous materials, such as fiberglass, matted or woven cloth Laminated sheet structures of this type are referred to in this patent as disclosed in U.S. Pat. Nos. 3,193,437; 3,192,441; and 3,944,707.
Improved composite structures are disclosed in U.S. Pat. No. 4,250,136. An amorphous or uncured core element is used which comprises a mixture of small and large organic (e.g. polystyrene or phenolic) or inorganic (e.g. clay, quartz, or glass) hollow spheres having diameters, for example, in the range of 10 to 15,000 microns and a wall thickness of 0.2 to 200 microns. Suitable matrices can be an organic resin such as an epoxy, a polyester, or a vinyl ester resin.
Energy absorbing materials which are composites useful in the manufacture of automobile bumpers and other devices intended to provide protection against damage due to impact, shock, or collision, are disclosed in U.S. Pat. No. 4,101,704. These composites utilize a polymer matrix which can be a polyurethane polymer having dispersed therein rigid, hollow bodies composed of a phenolic resin, glass, silica, or carbon.
A foam composite useful as an insulating board is disclosed in U.S. Pat. No. 4,877,671 as having a first and second oppositely disposed corrugated skin and a core of a foam material therebetween. The foam core is a phenolic foam.
A material for use as a reinforcing core in a structure is disclosed in U.S. Pat. No. 4,522,860. Reinforcing structures are also disclosed in U.S. Pat. Nos. 3,825,465, 3,376,684, 3,591,351 and 3,869,778.
In each of the composites disclosed in the prior art, improved resistance to lateral impact loads is desirable. The composite of the present invention provides for a novel structure which is specifically intended to provide improved resistance to lateral impact loads, as a consequence of the improved ability of the composite to transfer the impact load to adjacent areas so as to allow the composite to sequentially deform under load. The composite automobile body panels of the prior art, composed of a light weight plastic material, require substantially increased lateral impact resistance in order to replace the presently used sheet steel body panels.